/**
* @class Ext.ux.TreeCheckNodeUI
* @extends Ext.tree.TreeNodeUI
*
* 对 Ext.tree.TreeNodeUI 进行checkbox功能的扩展,后台返回的结点信息不用非要包含checked属性
*
* 扩展的功能点有：
* 一、支持只对树的叶子进行选择
*    只有当返回的树结点属性leaf = true 时，结点才有checkbox可选
*    使用时，只需在声明树时，加上属性 onlyLeafCheckable: true 既可，默认是false
*
* 二、支持对树的单选
*    只允许选择一个结点
*    使用时，只需在声明树时，加上属性 checkModel: "single" 既可
*
* 二、支持对树的级联多选
*    当选择结点时，自动选择该结点下的所有子结点，或该结点的所有父结点（根结点除外），特别是支持异步，当子结点还没显示时，会从后台取得子结点，然后将其选中/取消选中
*    使用时，只需在声明树时，加上属性 checkModel: "cascade" 或"parentCascade"或"childCascade"既可
*
* 三、添加"check"事件
*    该事件会在树结点的checkbox发生改变时触发
*    使用时，只需给树注册事件,如：
*    tree.on("check",function(node,checked){...});
*
* 默认情况下，checkModel为'multiple'，也就是多选，onlyLeafCheckable为false，所有结点都可选
*
* 使用方法：在loader里加上 baseAttrs:{uiProvider:Ext.ux.TreeCheckNodeUI} 既可.
* 例如：
*   var tree = new Ext.tree.TreePanel({
*   el:'tree-ct',
*   width:568,
*   height:300,
*   checkModel: 'cascade',   //对树的级联多选
*   onlyLeafCheckable: false,//对树所有结点都可选
*   animate: false,
*   rootVisible: false,
*   autoScroll:true,
*   loader: new Ext.tree.DWRTreeLoader({
*    dwrCall:Tmplt.getTmpltTree,
*    baseAttrs: { uiProvider: Ext.ux.TreeCheckNodeUI } //添加 uiProvider 属性
*   }),
*   root: new Ext.tree.AsyncTreeNode({ id:'0' })
* });
* tree.on("check",function(node,checked){alert(node.text+" = "+checked)}); //注册"check"事件
* tree.render();
*
*/
 
Ext.ux.TreeCheckNodeUI = function() {
//多选: 'multiple'(默认)
//单选: 'single'
//级联多选: 'cascade'(同时选父和子);'parentCascade'(选父);'childCascade'(选子)
this.checkModel = 'multiple';

//only leaf can checked
this.onlyLeafCheckable = false;

Ext.ux.TreeCheckNodeUI.superclass.constructor.apply(this, arguments);
};
 
Ext.extend(Ext.ux.TreeCheckNodeUI, Ext.tree.TreeNodeUI, {
 
    renderElements : function(n, a, targetNode, bulkRender){
    var tree = n.getOwnerTree();
   this.checkModel = tree.checkModel || this.checkModel;
   this.onlyLeafCheckable = tree.onlyLeafCheckable || false;
    
        // add some indent caching, this helps performance when rendering a large tree
        this.indentMarkup = n.parentNode ? n.parentNode.ui.getChildIndent() : '';
 
        //var cb = typeof a.checked == 'boolean';
   var cb = (!this.onlyLeafCheckable || a.leaf);
        var href = a.href ? a.href : Ext.isGecko ? "" : "#";
        var buf = ['<li class="x-tree-node"><div ext:tree-node-id="',n.id,'" class="x-tree-node-el x-tree-node-leaf x-unselectable ', a.cls,'" unselectable="on">',
            '<span class="x-tree-node-indent">',this.indentMarkup,"</span>",
            '<img src="', this.emptyIcon, '" class="x-tree-ec-icon x-tree-elbow" />',
            '<img src="', a.icon || this.emptyIcon, '" class="x-tree-node-icon',(a.icon ? " x-tree-node-inline-icon" : ""),(a.iconCls ? " "+a.iconCls : ""),'" unselectable="on" />',
            cb ? ('<input class="x-tree-node-cb" type="checkbox" ' + (a.checked ? 'checked="checked" />' : '/>')) : '',
            '<a hidefocus="on" class="x-tree-node-anchor" href="',href,'" tabIndex="1" ',
             a.hrefTarget ? ' target="'+a.hrefTarget+'"' : "", '><span unselectable="on">',n.text,"</span></a></div>",
            '<ul class="x-tree-node-ct" style="display:none;"></ul>',
            "</li>"].join('');
 
        var nel;
        if(bulkRender !== true && n.nextSibling && (nel = n.nextSibling.ui.getEl())){
            this.wrap = Ext.DomHelper.insertHtml("beforeBegin", nel, buf);
        }else{
            this.wrap = Ext.DomHelper.insertHtml("beforeEnd", targetNode, buf);
        }
       
        this.elNode = this.wrap.childNodes[0];
        this.ctNode = this.wrap.childNodes[1];
        var cs = this.elNode.childNodes;
        this.indentNode = cs[0];
        this.ecNode = cs[1];
        this.iconNode = cs[2];
        var index = 3;
        if(cb){
            this.checkbox = cs[3];
            Ext.fly(this.checkbox).on('click', this.check.createDelegate(this,[null]));
            index++;
        }
        this.anchor = cs[index];
        this.textNode = cs[index].firstChild;
    },
   
    // private
    check : function(checked){
        var n = this.node;
   var tree = n.getOwnerTree();
   this.checkModel = tree.checkModel || this.checkModel;
  
   if( checked === null ) {
    checked = this.checkbox.checked;
   } else {
    this.checkbox.checked = checked;
   }
  
   n.attributes.checked = checked;
   tree.fireEvent('check', n, checked);
  
   if(this.checkModel == 'single'){
    var checkedNodes = tree.getChecked();
    for(var i=0;i<checkedNodes.length;i++){
     var node = checkedNodes[i];
     if(node.id != n.id){
      node.getUI().checkbox.checked = false;
      node.attributes.checked = false;
      tree.fireEvent('check', node, false);
     }
    }
   } else if(!this.onlyLeafCheckable){
    if(this.checkModel == 'cascade' || this.checkModel == 'parentCascade'){
     var parentNode = n.parentNode;
     if(parentNode !== null) {
      this.parentCheck(parentNode,checked);
     }
    }
    if(this.checkModel == 'cascade' || this.checkModel == 'childCascade'){
     if( !n.expanded && !n.childrenRendered ) {
      n.expand(false,false,this.childCheck);
     }else {
      this.childCheck(n); 
     }
    }
   }
},
 
   
    // private
childCheck : function(node){
   var a = node.attributes;
   if(!a.leaf) {
    var cs = node.childNodes;
    var csui;
    for(var i = 0; i < cs.length; i++) {
     csui = cs[i].getUI();
     if(csui.checkbox.checked ^ a.checked)
      csui.check(a.checked);
    }
   }
},

// private
parentCheck : function(node ,checked){
   var checkbox = node.getUI().checkbox;
   if(typeof checkbox == 'undefined')return ;
   if(!(checked ^ checkbox.checked))return;
   if(!checked && this.childHasChecked(node))return;
   checkbox.checked = checked;
   node.attributes.checked = checked;
   node.getOwnerTree().fireEvent('check', node, checked);
  
   var parentNode = node.parentNode;
   if( parentNode !== null){
    this.parentCheck(parentNode,checked);
   }
},

// private
childHasChecked : function(node){
   var childNodes = node.childNodes;
   if(childNodes || childNodes.length>0){
    for(var i=0;i<childNodes.length;i++){
     if(childNodes[i].getUI().checkbox.checked)
      return true;
    }
   }
   return false;
},

    toggleCheck : function(value){
    var cb = this.checkbox;
        if(cb){
            var checked = (value === undefined ? !cb.checked : value);
            this.check(checked);
        }
    }
});